Fresh cells were crosslinked with 2 mM disuccinimidyl glutarate (DSG) for 30 min, followed by 1% formaldehyde for 10 min at room temperature. Nuclei were isolated, sonicated and incubated with magnetic bead-antibody complexes. ChIPed DNA was processed using Takara SMRTer ThruPLEX DNA-seq Kit. Briefly, DNA was end-repaired and ligated to stem-loop adaptors. Then DNA was PCR amplified with Illumina-compatible primers for 7-11 cycles and library fragments of 200 to 400 bp were selected using Ampure XP beads.